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Old 06-21-2015, 07:26 PM   #1
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High-tech generator-less motorhome

I just got my MotorHome magazine which has a review of the Roadtrek CS Adventurous with the E-trek option. As mentioned in the recent "AC temperature" thread, I find the general concept of relying on high-capacity batteries and inverter in lieu of a generator intriguing. There are both pros and cons, and wonder what others think about such a system.

Basically in the reviewed motorhome the Mercedes engine powers a second dedicated 3,500-watt alternator/generator, which charges (8) 6-Volt AGM batteries, which then power a 5,000 watt inverter.

With a setup like this one could run the rooftop AC, electric refrigerator, and charge batteries while driving without need of a generator. Other than a little added weight and cost, the biggest drawback I see versus a generator is not being able to run the AC for long periods while boondocking.

What do you think? Glimpse of the future or technology for sake of being different?
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Old 06-22-2015, 09:47 AM   #2
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I am sure that as soon as the RV manufacturers figure out that many people never use their generators, they will quit supplying them in motorhomes as standard equipment as a cost-cutting measure.

I have no idea if most people use their generators or don't. We hardly ever use ours as it is loud and it uses a lot of gas.

For example, our built-in generator burns about 1/2 gallon per hour, and it uses our engine's 55 gallon gas tank. Since the generator will not run if the tank is less than 1/4 full, that gives us approx 40 gallons or 80 hours if we fill our tank just prior to boondocking.

Three days is not a long time when we boondock. Of course, we don't have to run the generator for 24 hours a day, and in some cases you are not allowed to run it at night, if you need air conditioning, you probably want to run it constantly.

We have a left over Honda EU2000 from our boating days, and if we boondock, we use that generator instead. It uses a lot less gas and it can run 24 hours on just a couple of gallons. As well, it is a lot quieter.

True, it is not powerful enough to run the A/C, but we have not been in a situation (yet) where that has been a problem. And we always have the option of firing up the big genny if we need A/C for a few hours - so at minimum, the EU2000 supplements the built-in genny.

We usually start the EU2000 up in the morning so we can make coffee, and let it run all day into the early evening to keep the batteries charged, then shut it down at night. The fridge runs on LP at night when we do that. The only convenience we don't have with the genny powered down is use of the microwave, the bedroom TV (the salon TV is 12V), and the A/C.

We would not likely go out and buy a EU2000 if we didn't already have it from our boating days, especially with a built-in generator in the motorhome. But we have it, so we might as well use it.

We have, on occasion, run our built-in generator to keep the fridge running while traveling, but we have found that if we start the fridge the day before and get it cooled down to operating temperature, we can leave it off for up to 4 hours as we travel. It will stay cold enough without any power for that time period. Of course, if we are traveling longer distances, we'll need to run the genny to keep it cold.

We do keep a thermometer in the fridge so we know when to start the genny in this situation.

Not sure how others use their built-in generators for boondocking, but with the limited run time (limited to the gas tank size), I am not sure how often they are used. Seems even an engine powered alternator such as the Mercedes would have this issue when boondocking. Of course if you didn't need to run it constantly, it would improve things.
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Old 06-22-2015, 11:33 AM   #3
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If I had a system that ran completely off of batteries like that with an inverter the first thing I would add is a ton of solar cells on the roof.

In our case: We've never boondocked. We rarely camp without full hookups. We will use the odd electric only site occasionally. Hence we never have a need to run the generator whilst camping.

Our generator gets used quite a bit though: While going down the road. I'll run it to use the roof top A/C, or my son will want it on to use the Playstation. Since it is quite noisy I'll only run it when we travel down larger roads and interstates--try to keep it off if we find ourselves in a residential area.
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Old 06-22-2015, 12:32 PM   #4
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I read the same article in Motorhome magazine.

158K for a class B motorhome that you must kneel in the aisles to load the refrigerator and one that is plagued by exhaust emissions problems.

Let's see no generator and uses an inverter and 6 batteries, yep good for boon docking.

10 gal black water, 21 gal grey water, 33 gal fresh water maybe good for three days most

The thing I find interesting about the article is they do not mention why their price as tested is 30,000 more than the MSRP. Is that the cost of the inverter, alternator and batteries?

Let's see the technology transfer to a Class A at a reasonable cost and then I'll consider whether or not it's worth the cost.
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Old 06-22-2015, 02:34 PM   #5
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an onboard generator was on my high list....a primary reason for getting a motorhome over a TT.
I'm not boondocking for days running it 24/7, but I love the ability to run the AC off grid.
We use it on super hot days on the highway for the house AC, and have used it a few times stopping for a few hours in the evening before bed or for a lunch break or such.... and for my morning coffee

An big inverter battery system like this with engine mounted alternator would work too for most of my needs, and i can imagine a day when this type of idea will overtake current technology.

I have often wondered why they don't install a smaller generator in place of the onans, more like the honda that FW describes. Maybe a hybrid of an inverter system, plus a smaller generator like his Honda on ly integrally mounted, to supplement for longer term needs might be an answer

Another thought..... my wife's honda van has technology now that automatically shuts down cylinders when the power isn't needed. I can imagine a chassis engine mounted generator, where the engine could run on reduced cylinders for extended idle times..... why carry around two engines when one will do?
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Old 06-22-2015, 02:42 PM   #6
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...
Another thought..... my wife's honda van has technology now that automatically shuts down cylinders when the power isn't needed. I can imagine a chassis engine mounted generator, where the engine could run on reduced cylinders for extended idle times..... why carry around two engines when one will do?
I was looking at a riding mower a week ago that has the ability to flip a switch and it converts from mower to generator to power electric tools such as trimmers or pole saws. At $5,000 I thought it was a little pricey and want to see which direction the price heads and what type of demand they have for the units.
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Old 06-22-2015, 02:51 PM   #7
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If I had a system that ran completely off of batteries like that with an inverter the first thing I would add is a ton of solar cells on the roof.

In our case: We've never boondocked. We rarely camp without full hookups. We will use the odd electric only site occasionally. Hence we never have a need to run the generator whilst camping.

Our generator gets used quite a bit though: While going down the road. I'll run it to use the roof top A/C, or my son will want it on to use the Playstation. Since it is quite noisy I'll only run it when we travel down larger roads and interstates--try to keep it off if we find ourselves in a residential area.
I did not mention that the E-Trek option includes a 240-watt solar charging system, separately priced at $3,120. On a good day you might get about 1 kWh out of it which is about 20-minutes worth out of alternator/generator, so while it could help it's a small contributor for campers who drive their motorhome daily -- unless on campground shore power.

Looking at their website and comparing models, I can't even find a diesel generator for the Adventorous model. The base unit also comes with separate van-engine-driven 3500-watt alternator/generator, but with smaller inverter and only four house batteries instead of eight. Still plenty to run TVs, lights, microwave, coffee maker, etc... for extended periods.

For your described use requiring the generator mostly to power the AC while driving, it seems a system like the E-Trek would function very nicely. The second alternator/generator could easily power an air conditioner while driving, with plenty of capacity to spare. A typical AC uses about 1500 watts so alternator/generator would run at about half load.
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Old 06-22-2015, 02:57 PM   #8
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Here is another thought: What if, in the future, someone designs an EV RV! Now there is no gas or propane; just a ton of Li-Ion batteries in the chassis (or whatever the new tech battery is called).

Now your only option is an inverter (and solar cells) to keep the thing running.

Sure that day is a long way off given that most EV's these days go less than 100 miles (mine can barely make 100 miles if I stretch it; of course Tesla's not withstanding).

Also keep in mind that there are now battery buses and battery garbage trucks.
Electric Garbage Trucks: Huge Energy Savings And They Won't Wake You Up In The Morning - Forbes
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Old 06-22-2015, 03:05 PM   #9
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....cut....

Not sure how others use their built-in generators for boondocking, but with the limited run time (limited to the gas tank size), I am not sure how often they are used. Seems even an engine powered alternator such as the Mercedes would have this issue when boondocking. Of course if you didn't need to run it constantly, it would improve things.
One of the cons I see to Sprinter diesel, or most any new diesel, is that they don't like to idle for long periods. Other than that, as if this technology was applied with gasoline engine, you could fast idle the engine for much less than an hour a day and probably get all the juice you need as long as running an AC is not required.

For those camping in cool or even cold weather with propane heat, it may be possible to eliminate the traditional Onan generator. Having to run an AC for more than two hours off the grid is probably the one item that makes this type of system impractical more than anything else.
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Old 06-22-2015, 03:11 PM   #10
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One of the cons I see to Sprinter diesel, or most any new diesel, is that they don't like to idle for long periods. Other than that, as if this technology was applied with gasoline engine, you could fast idle the engine for much less than an hour a day and probably get all the juice you need as long as running an AC is not required.

For those camping in cool or even cold weather with propane heat, it may be possible to eliminate the traditional Onan generator. Having to run an AC for more than two hours off the grid is probably the one item that makes this type of system impractical more than anything else.
And in some localities idling the engine is good for between 150.00 - 500.00 plus court costs (per occurrence) since idling engines is illegal and against municipality codes.

On Connecticut idling a truck engine for three minutes can cost the trucker 25,000. Would this also apply to RVs. And in these instances the state of registration has no bearing on whether or not you are in compliance.
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Old 06-22-2015, 03:19 PM   #11
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I read the same article in Motorhome magazine.

158K for a class B motorhome that you must kneel in the aisles to load the refrigerator and one that is plagued by exhaust emissions problems.

Let's see no generator and uses an inverter and 6 batteries, yep good for boon docking.

10 gal black water, 21 gal grey water, 33 gal fresh water maybe good for three days most

The thing I find interesting about the article is they do not mention why their price as tested is 30,000 more than the MSRP. Is that the cost of the inverter, alternator and batteries?

Let's see the technology transfer to a Class A at a reasonable cost and then I'll consider whether or not it's worth the cost.
Dave, the technology, or its concept at least, isn't tied to the size of the RV. Obviously a tiny Class B doesn't have the size of your Class A, but that shouldn't affect how the same equipment could be installed and used in other motorhomes. The biggest limitation I see at present is that only Mercedes offers an optional bracket to install a second generator. I guess Ford could but doesn't yet.

I did pick up on the price, but as bad as it looks, I'm not sure it's that bad compared to having to install a diesel generator.

The E-Trek option is listed at $13,260, with $3,120 of that being the solar charging system. The difference of about $10,000 is comparable with what Sportsmobile charges for a very small diesel generator that fits under a van. And the E-Trek option includes other features besides solar that makes the cost differential even closer.
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Old 06-22-2015, 03:39 PM   #12
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Here is another thought: What if, in the future, someone designs an EV RV! Now there is no gas or propane; just a ton of Li-Ion batteries in the chassis (or whatever the new tech battery is called).

Now your only option is an inverter (and solar cells) to keep the thing running.

Sure that day is a long way off given that most EV's these days go less than 100 miles (mine can barely make 100 miles if I stretch it; of course Tesla's not withstanding).

Also keep in mind that there are now battery buses and battery garbage trucks.
Electric Garbage Trucks: Huge Energy Savings And They Won't Wake You Up In The Morning - Forbes
If/when plug-in hybrid vans make it to market, they will likely be first motorhomes to have an electric air conditioner compressor like is typical for hybrids, which means that the need for separate roof-mounted ACs may not be needed. With software revisions it should be possible to power the AC for extended periods from the batteries or from the built-in vehicle charger.

Since my van has factory dual AC I "briefly" thought of modifying it to run on 110 Volts and then adding a high-capacity alternator in place of the AC compressor, to end up with similar operation to E-Trek, except just one AC instead of two. I just couldn't justify the cost for all the modifications. However, if done that way initially from Ford factory it would be very affordable.
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Old 06-22-2015, 03:45 PM   #13
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And in some localities idling the engine is good for between 150.00 - 500.00 plus court costs (per occurrence) since idling engines is illegal and against municipality codes.
Good point. Can you run your generator under same conditions?

Just curious because I'd bet that it's louder and uses more fuel than a Sprinter 4-cylinder diesel while fast idling.

Regardless, the reason to have 9600 watt-hours of battery capacity is so you don't need to run the engine too often.
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Old 06-22-2015, 04:04 PM   #14
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If/when plug-in hybrid vans make it to market, they will likely be first motorhomes to have an electric air conditioner compressor like is typical for hybrids, which means that the need for separate roof-mounted ACs may not be needed. With software revisions it should be possible to power the AC for extended periods from the batteries or from the built-in vehicle charger.

Since my van has factory dual AC I "briefly" thought of modifying it to run on 110 Volts and then adding a high-capacity alternator in place of the AC compressor, to end up with similar operation to E-Trek, except just one AC instead of two. I just couldn't justify the cost for all the modifications. However, if done that way initially from Ford factory it would be very affordable.
That alternator driven by a belt on the engine is drawing anywhere from 1 to 5 HP from the engine. This means the engine must run at higher RPMs to maintain the same speed over a given distance. The running at higher RPMs means the MPG rating on the vehicle decreases which has an impact on "Ford's" compliance with US Gov't CAFE standards. This means that Ford would have to find other efficiencies to maintain their compliance with the standards and those efficiencies may or may not be available. Since Ford does not design the body they cannot improve the aerodynamic characteristics of the vehicle. I guess they could install tires that have no grip and thereby reduce friction.

I would not assume Ford could do something more affordable. Government regulations in other areas may create a situation whereby what you are asking for is beyond reach.
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Old 06-22-2015, 05:20 PM   #15
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The running at higher RPMs means the MPG rating on the vehicle decreases which has an impact on "Ford's" compliance with US Gov't CAFE standards
CAFE standards only apply to "light duty" vehicles. Note that if you purchase an F-250 or an F-350 mpg is NOT on the window sticker. (Light duty vehicles = vehicles weighing less than 8800 lbs.) About the only thing that is regulated is the tailpipe emissions, but the fuel consumption is not.

Really its only now that medium and heavy duty vehicles are even remotely being considered for some sort of mileage standard.
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Old 06-22-2015, 05:39 PM   #16
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In 2005-2006 there was some serious announcements being made by Atwood Industries that they were developing a propane powered fuel cell for RVs.


That development would redefined power generation and power consumption for RVs. It would make all discussions about 6v golf cart batteries, solar panels, miserly usage, and generator maintenance and problems a moot point. It would also have seriously destroyed many existing businesses, (generators, batteries, solar, water heaters, furnaces, and associated maintenance industries).


The fuel cell was capable of generating on-demand 5000 watts, it also heated water, provided heat as a supplementary furnace, and it produced fresh distilled water, (normally just thrown away). Fuel cell technology does exist and kept on being developed and it has caught on in military and hospital emergency power applications, but not so much for RVs.


In mass produced quantities, an RV sized unit would cost just as much a common non-fuel injected gasoline 5000Watt Onan generator.


Since those heady times. the whole discussion about RV appliances completely gravitated towards on-demand water heaters and residential refrigerators.
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Old 06-22-2015, 05:49 PM   #17
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2001:
Atwood to Develop Fuel-Cell Power System

Here is more: IdaTech and Atwood Mobile Products Announce Alliance to Develop Recreational Vehicle Fuel Cell Power System

Although, it would appear their "Fuel Cell" is only being used in the leak detectors currently:
LP & CO Gas Alarm (pdf)

My take: a propane powered fuel cell would be great for an RV. As mentioned by Beacher it could supplant a bunch of RV systems. However, my experience with driving an EV around and reading in EV forums similar to our Thor forum here leads me to believe that they couldn't get it cost-effective enough to work. Fuel cell cars have been "10 years away" now for quite some time (even though Toyota has theirs now just coming out there is only like 3 stations nationwide to fill them up--all in California). There must be something fundamentally too expensive to get fuel cells up and running (yes its the same with EVs, however battery costs for EVs have been falling like a rock lately).
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Old 06-22-2015, 06:24 PM   #18
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CAFE standards only apply to "light duty" vehicles. Note that if you purchase an F-250 or an F-350 mpg is NOT on the window sticker. (Light duty vehicles = vehicles weighing less than 8800 lbs.) About the only thing that is regulated is the tailpipe emissions, but the fuel consumption is not.

Really its only now that medium and heavy duty vehicles are even remotely being considered for some sort of mileage standard.
The other discussion occurring is basing the vehicles under CAFE standards on the square footage of the footprint rather than on GVWR and also reducing the square footage required for compliance. I guess some of the manufactures decided they could skirt the requirement by reducing the vehicle footprint and the government is going to respond.

The point I was making is there are tradeoffs. If adding the additional alternator increase fuel consumption from 8 to 6 MPG how many people are going to back away from the market.

Also, a 13,000 dollar option package at 2.50 per gallon will buy over 5,000 gallons of fuel, which at .9 gph of gen run time equates to 5777 hours. The break even point for me would be somewhere in 8 to never range. My prior coach had less than 300 hours on the generator and my current coach has less than 50.

For me to shell out that kind of money for a coach where I have to kneel in the aisle to load the refrigerator and never see a return on investment just doesn't make any sense outside the "cool factor". I buy practical and useful, I don't by cool especially since cool is usually short lived or constantly changing.
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Old 06-22-2015, 06:34 PM   #19
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this thread got me to thinking so I went and checked.... in 1 years time, i have put approx 30 hours on my generator. a little bit of that was solely for the purpose of exercising it, but mostly real use.

Not a lot, but I wouldn't want to do without it, or at least an equivalent solution
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Old 06-22-2015, 06:51 PM   #20
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That alternator driven by a belt on the engine is drawing anywhere from 1 to 5 HP from the engine. This means the engine must run at higher RPMs to maintain the same speed over a given distance.

....cut.....
The engine would most likely run at same speed but slightly higher torque to produce the extra power. Large motorhomes like yours cruise at roughly 100 HP on level roads, so an additional 1 to 5 HP would not necessarily require different gearing or downshifts just because of relatively-minor extra alternator load.

Even if there was EPA testing, the second alternator like Mercedes supplies the mounting bracket for can be installed by the RV manufacturer, just like they add generators. Even if Ford supplied the second alternator/generator it wouldn't affect MPGs as long as a load wasn't placed on it. Without the house AC running off the 110-Volt inverter system it wouldn't put an extra load on the chassis' engine (for all practical purposes -- extra weight of alternator is insignificant).

In any case I'm fairly certain that total fuel consumption while driving down the road would be lower than running a generator at close to 1 gallon per hour. It's tough to see the government preventing this from happening solely from an environmental basis.
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